EMULSION BASICS. Midwestern Pavement. Adam Redman Heritage Research Group October 28, 2010 Des Moines, Iowa

Transcription

1 EMULSION BASICS Midwestern Pavement Preservation Partnership Adam Redman Heritage Research Group October 28, 2010 Des Moines, Iowa

2 OVERVIEW History Testing Description Storage and Handling Performance Composition Production Classifications

3 HISTORY OF ASPHALT EMULSIONS First developed in the 1900 s In the 20 s asphalt emulsions came into general use for paving applications Early use was in spray applications and dust control.

4 HISTORY OF ASPHALT EMULSIONS Interest picked up in the 50 s for farm to market roads

5 HISTORY OF ASPHALT EMULSIONS The environmental movement in the 1970 s prompted the increase in emulsion manufacturing due to concerns about pollution from cutback asphalts (VOC s)

6 HISTORY OF ASPHALT EMULSIONS New formulations have increased performance for many applications

7 WHAT IS AN ASPHALT EMULSION? Two liquids or components with one dispersed continuously through the other The immiscible materials are held together in a stable suspension with the aid of a surfactant Examples of common emulsions are shampoo, milk, mayonnaise and paint

8 OIL & WATER EMULSION NOT STABILIZED Unstable emulsion. Not an emulsion.

9 WHICH WILL COME OUT ON TOP?

10 OIL & WATER EMULSION STABILIZED Oil and water can be emulsified (stabilized) when a surfactant is added.

11 HOW EMULSIFIERS WORK Both cationic and anionic emulsifiers are surfactants (soaps) Gives stability to the emulsion Does not allow the Oil (asphalt) to separate from the water. Gives a charge Cationic vs. Anionic (Positive vs. Negative) Imparts setting characteristics Slow Set, Medium Set and Quick Set

12 ANIONIC EMULSIFIER STRUCTURE CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 O Tail Group: Hydrocarbon, lipophilic (Oil loving) CH 2 CH 2 CH 2 C COO Na + Head Group: Polar, hydrophilic (Water loving)

13 SURFACTANT MODEL Sodium Hydroxide Tall Oil o c c c c c c c Nao c c c c c Polar Head (Water Loving) NonPolar Tail (Oil Loving Hydrocarbon)

14 ASPHALT EMULSION MODEL Asphalt Droplet Surfactant Water

15 Cationic Anionic Repulsion Repulsion Never Mix Emulsions + Attraction

16 CHEMICAL SET Rapid Medium Slow

17 NAMING THE EMULSIONS Prefix RS = rapid set SS = slow set QS = quick set MS = medium set HFRS = high float rapid set C = Cationic AE = anionic emulsion Suffix 90,150, or 300 = penetration ranges h = hard penetration P,M or L = modified with polymer or latex 1 = low viscosity, cooler temps 2= high viscosity, higher temps

18 NOMENCLATURE HFRS2 High Viscosity High Float Rapid Setting CRS2P High Viscosity, Polymer Modified Cationic Rapid Setting CSS1h Low Viscosity, hard asphalt Cationic Slow Setting

19 MODIFICATIONS Polymers SBS & SBR Large Molecules Increase Service Life of the Project Early Chip Retention Flexibility Elasticity

20 FLUORESCENCE OPTICAL MICROSCOPE 4% SBS in Asphalt

21 GENERAL CLASSIFICATION RapidSetting MediumSetting SlowSetting QuickSetting and MicroSurfacing

22 RAPID SETTING EMULSION Designed to react quickly with aggregate and revert from the emulsion to the asphalt. Primarily used for spray applications. RS2, HFRS2, MWS90, and CRS2

23 SURFACE TREATMENT APPLICATION

24 MEDIUM SETTING EMULSION Designed for mixing with graded aggregate. Formulated not to break immediately upon contact with aggregate and will remain workable for a few minutes to several months depending upon the formulation. Primarily used in pugmills. MS2, CMS2, HFMS2, MWS150 & 300

25 COLD CONSTRUCTED ASPHALT PAVEMENTS

26 SLOWSETTING EMULSION Designed for mixing stability. Primarily used with high fine content aggregates, tack coats, fog seals and dust palliatives. SS1h, Dustlay, Dust Control

27 QUICKSETTING & MICRO SURFACING Designed specifically for slurry and microsurfacing emulsions. Allows quicker opening to traffic times. Microsurfacing emulsions are polymer modified and allow mixes to be placed at greater thickness than slurry seals. CSS1h, CQS1h and CQS1hM

28 MICRO SURFACING / SLURRY

29 EMULSION PRODUCTION

30 EMULSION MILL Colloid Mill Rotor & Stator

31 EMULSION PARTICLE SIZE Asphalt emulsion 110 Microns in size Human Hair Microns in size

32 VERTICAL TANKS Vertical storage tanks are recommended. Tanks should be insulated to protect the emulsion from freezing. There is less surface area which means there is less exposure of the emulsion to air. These tanks are easier to put into place, heat, insulate and keep track of inventory.

33 STORAGE TEMPERATURES Recommended Storage Temperatures Always consult the manufacture for their recommended storage temperatures Emulsion MINºF MAXºF RS RS HFRS SS1h AE MS CQS1h CSS1hM CRS CRS2P

34 STORAGE AND HANDLING Flocculation when the particles stick together. Reasons for this maybe due to a low chemical load, thermal shock, and prolonged storage.

35 STORAGE AND HANDLING Coalescence particles that stick together become larger. Reasons for this maybe due to flocculation.

36 STORAGE AND HANDLING Settlement the heavier asphalt particles settle to the bottom of the tank. Reasons for this maybe prolonged storage, lack of mixing, problems with asphalt compatibility or wrong chemical load.

37 PARTICLE SIZE AFFECTS EMULSION BREAKDOWN Variable Size Pack Efficiently Same Size Pack Poorly Poor Packing is More Stable and Produces Higher Viscosity

38 VISCOSITY IS RELATED TO QUANTITY OF EXTERNAL PHASE AND PACKING Low Asphalt Content Low Viscosity High Asphalt Content High Viscosity

39 STORING ASPHALT EMULSIONS DO store as you would water between 50ºF and 185ºF, depending on the intended use and specific product. DO store at the temperature specified for the particular grade and application. DO NOT permit the asphalt emulsion to be heated above 185ºF. Elevated temperatures evaporate water, changing the characteristics of the asphalt emulsion. DO NOT let the emulsion freeze. This breaks the emulsion, separating the asphalt from the water. The result will be two layers in the tank, neither of which will be suited for the intended use. DO NOT allow the temperature of the heating surface to exceed 212ºF. This will cause premature breakdown of the emulsion on the heating surface. DO NOT use forced air to agitate the emulsion. It may cause the emulsion to break. Chapter Three from the Basic Asphalt Emulsion Manual. The Asphalt Institute

40 HANDLING EMULSIFIED ASPHALTS DO when heating emulsified asphalt agitate it to eliminate or reduce skin formation. DO protect pumps, valves, and lines from freezing in winter. Drain pumps or fill them with antifreeze according to the manufacture s recommendations. DO blow out lines and leave drain plugs open when they are not in service. DO use pumps with proper clearances for handling emulsified asphalt. Tightly fitting pumps can cause binding and seizing. DO use a mild heating method to apply heat to the pump packing or casing to free a seized pump. Discourage the use of propane torches. DO warm the pump to about 150ºF (65ºC) to ease startup DO when a pump is to be out of service for even a short period of time, fill it with fuel oil to ensure a trouble free startup. DO before dilution grades of emulsified asphalt, check the compatibility of the water with emulsion (not the emulsion to the water). DO if possible, use warm water for dilution and always add the water slowly to the emulsion (not the emulsion to the water). DO avoid repeated pumping and recycling, if possible, as the viscosity may drop and air may become entrained, causing the emulsion to be unstable. Chapter Three from the Basic Asphalt Emulsion Manual. The Asphalt Institute

41 HANDLING EMULSIFIED ASPHALTS DO guard against mixing different classes, types, and grades of emulsified asphalt in storage tanks, transports, and distributors. For example, if cationic and anionic emulsified asphalts are mixed, the blend will break and separate into water and coagulated asphalt that will be difficult to remove. Because it is hard to determine visually the difference between various emulsified asphalts, always make a trial blend of the newlydelivered emulsion and the stored emulsion before pumping off. Check the trial blend for compatibility. DO place inlet pipes and return lines at the bottom of tanks to prevent foaming. DO pump from the bottom of the tank to minimize contamination from skinning that may have formed. DO remember that emulsions with the same grade designation can be very different chemically and in performance. DO haul emulsion in truck transports with baffle plates to prevent sloshing. DO mix by circulation, or otherwise, emulsions that have been in prolonged storage. Chapter Three from the Basic Asphalt Emulsion Manual. The Asphalt Institute

42 HANDLING EMULSIFIED ASPHALTS DO NOT use tightfitting pumps for pumping emulsified asphalt; they may seize or shear the asphalt emulsion. DO NOT apply severe heat to pump packing glands or pump casing. The pump may be damaged and the asphalt may become even harder. DO NOT dilute rapidsetting grades of emulsified asphalt with water. Medium and slow setting grades may be diluted, but always add water slowly to the asphalt emulsion. Never add the asphalt emulsion to a tank of water when diluting. DO NOT recirculate emulsified asphalts for too many cycles. They tend to lose viscosity when subjected to excessive pumping. Also, air bubbles may become entrained which would render the emulsion unstable. DO NOT load emulsified asphalt into storage tanks, tank cars, tank transports, or distributors containing remains of incompatible materials. Chapter Three from the Basic Asphalt Emulsion Manual. The Asphalt Institute

43 WHY IS PROPER STORAGE AND HANDLING SO IMPORTANT? Quality of the emulsion Performance and application of the emulsion. COST!!!

44 TESTING OF EMULSIONS Composition Particle Charge Density Distillation Storage and Handling Storage Stability Sieve Saybolt Viscosity Reactivity Demulsibility Residue Tests Float Test Penetration Dynamic Shear Rheometer

45 PARTICLE CHARGE TESTER Used to identify the charge of the emulsion. Cationic (positive) Anionic (negative) Nonionic (no charge) ASTM D 244

46 SAYBOLT FUROL VISCOSITY Measure the viscosity of the emulsion. Test temperatures are 25ºC and 50ºC. Viscosity is defined as a fluid s resistance to flow. ASTM D 244

47 STORAGE STABILITY Indicates an emulsion s stability in storage. Sample is taken from the top and bottom after 24hrs. Residues can only differ by less than 1.0%. ASTM D 6930

48 OVERSIZED PARTICLES IN EMULSIFIED ASPHALT (Sieve Test) Test to measure the quality of an emulsion Excessive amounts of sieve (>0.1%) indicate emulsion instability. ASTM D 6933

49 DEMULSIBILITY Test indicates the relative rate at which the colloidal asphalt particles in an emulsion will break when mixed or spread on aggregate. Determines if the emulsion is rapid or slow setting. ASTM D 6936

50 EMULSION DENSITY Determines the density or weight per gallon on the emulsion. Emulsion s densities change depending on the asphalt content. Used for billing and inventory purposes. ASTM D 6937

51 DISTILLATION Used to separate the water from the asphalt. Measures the amount of asphalt in the emulsion. Additional tests are run on the residue that is recovered. ASTM D 6997

52 Float Test Measures the resistance to flow at elevated temperatures (140ºF). Float test is used for high float emulsions. ASTM D 13995

53 PENETRATION Used to determined the hardness of the asphalt. ASTM D 505

54 RING and BALL Measures the softening point properties of an asphalt or emulsion residue. First developed for the roofing and waterproofing industry. ASTM D 36

55 DYNAMIC SHEAR RHEOMETER Measures the rheological properties of an asphalt or emulsion residue. Developed for PG testing of asphalt binders

56 SUMMARY WHY USE EMULSIONS Emulsions reduce apparent viscosity of product Allow application temperature to be reduced Reduces application rate necessary to achieve coating on a surface To improve adhesion by chemically attracting emulsion droplets to surface using charge

57 DON T WANT FAILURES

58 WANT SUCCESSFUL PROJECTS

59 CONCLUSION The better that the materials are understood the better they can be used for their intended purpose Proper application is critical to success in pavements Use the resources of your emulsion supplier to achieve success in roads

60 THANK YOU Adam Redman Heritage Research Group 7901 W Morris Street Indianapolis, IN adam.redman@heritageenviro.com (317)